1. Field of the Invention
The present invention relates in general to current collectors and methods for manufacturing same, and, more particularly to a current collector device wherein an aluminum current collector having a reduced interfacial resistance, relative to other aluminum current collectors, is utilized.
2. The Prior Art
Various types of current collector devices for use in association with solid and/or liquid electrolytes have been known in the art for several years. For example, when used in association with lithium batteries, such current collectors have typically been constructed from nickel, stainless steel or aluminum. While all of such materials have proven as functional alternatives in such batteries, they do, nonetheless, exhibit several deficiencies.
Specifically, nickel and stainless steel, in addition to high cost, have a relatively high density. As a result of the use of such a relatively high density current collector, electrodes constructed using such a current collector exhibit a relatively low energy density. Furthermore, as known in the art, nickel oxidizes at a potential above 4 volts versus Li.sup.+ /Li.sup.0, and therefore, nickel current collectors cannot be used effectively at electrode voltages above that value.
Aluminum, on the other hand, which is quite inexpensive and which has a density of only 2.7 g/cc, eliminates the disadvantages associated with the use of nickel and/or stainless steel. Unfortunately, current collectors constructed from aluminum exhibit a relatively high interfacial resistance associated to the presence of a relatively thick native oxide layer which substantially uniformally covers its surface, which, in turn, results in a loss of energy and reduced power. Indeed, such a loss of energy and power is generally attributable to the fact that the aluminum's a native oxide layer 1) acts as an insulator, and thus severely limits electrical conductivity, and 2) greatly hinders adhesion of an electrochemically active electrode material which is to be directly, or indirectly applied to the surface of the aluminum current collector.
It is thus an object of the present invention to provide a current collector device and method of manufacturing same, wherein the device so made includes an aluminum current collector having a substantially reduced interfacial resistance and substantially increased adhesion capabilities relative to the prior art.
It is also an object of the present invention to provide a current collector device and method of manufacturing same, wherein the device has a modified native oxide layer on the surface of the aluminum current collector relative to the native oxide layer on the surface of prior art devices.
It is further an object of the present invention to provide a current collector device and method of manufacturing same, wherein an etching agent and a primer are both applied to the surface of the aluminum current collector in a single mixture so that actual etching of the aluminum oxide layer and adhesion of the primer to the surface of the aluminum can be accomplished by a single step.
These and other objects of the present invention will become apparent in light of the present Specification, Claims and Drawings.